package com.hmdp.service.impl;

import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.SimpleRedisLock;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService voucherService;
    @Resource
    private RedisIdWorker redisIdWorker;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static{
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
    //当从阻塞队列中获取元素时，如果队列中没有元素，则会一直阻塞直到有元素为止
    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private  void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    public class VoucherOrderHandler implements Runnable{
        @Override
        public void run() {
            while(true){
                try {
                    //1.获取队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    //2.创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常",e);
                }
            }
        }
    }


    /**
     * 创建订单
     * @param voucherOrder
     */
    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        //1.获取用户id
        Long userId = voucherOrder.getUserId();
        //2.创建锁对象
        SimpleRedisLock lock = new SimpleRedisLock("lock:" + userId, stringRedisTemplate);
        //3.尝试获取锁
        boolean success = lock.tryLock(1200);
        //4.判断获取锁是否成功
        if (!success) {
            //获取锁失败，返回错误信息
            log.error("获取失败");
            return;
        }
        //5.获取代理对象（事务）
        try {
             proxy.createVoucherOrder(voucherOrder);
        }
         finally {
            lock.unlock();
        }

    }
    private IVoucherOrderService proxy;


    /**
     * 秒杀优惠券
     *
     * @param voucherId
     * @return
     */
    @Override
    @Transactional
    public Result seckillVoucher(Long voucherId) {
        //获取用户id
        Long userId = UserHolder.getUser().getId();
        //1.执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(),
                userId.toString()
        );
        //2.判断结果是否为0
        int r = result.intValue();
        if(r != 0){
            //2.1不为0，代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        //2.2为0，有购买资格，把下单信息保存到阻塞队列
        VoucherOrder voucherOrder = new VoucherOrder();
        //2.3订单id
        long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        //2.4用户id
        voucherOrder.setUserId(userId);
        //2.5优惠券id
        voucherOrder.setVoucherId(voucherId);
        //2.6放入阻塞队列
        orderTasks.add(voucherOrder);
        //3.获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();
        return Result.ok(orderId);
  }
//    /**
//     * 秒杀优惠券
//     *
//     * @param voucherId
//     * @return
//     */
//    @Override
//    @Transactional
//    public Result seckillVoucher(Long voucherId) {
//        //1.查询优惠券信息
//        SeckillVoucher voucher = voucherService.getById(voucherId);
//        //2.判断秒杀是否开始
//        LocalDateTime beginTime = voucher.getBeginTime();
//        if (beginTime.isAfter(LocalDateTime.now())) {
//            //3.如果秒杀未开始，返回错误信息
//            return Result.fail("秒杀尚未开始！");
//        }
//        LocalDateTime endTime = voucher.getEndTime();
//        if (endTime.isBefore(LocalDateTime.now())) {
//            //秒杀已经结束
//            return Result.fail("秒杀已经结束！");
//        }
//        //4.判断库存是否充足
//        if (voucher.getStock() < 1) {
//            //5.如果不充足，返回错误信息
//            return Result.fail("库存不足！");
//        }
//        Long userId = UserHolder.getUser().getId();
//        //当用户id的值一样时，锁就一样，保证同一id用同一把锁
//        //创建锁对象
//        SimpleRedisLock lock = new SimpleRedisLock("lock:" + userId, stringRedisTemplate);
//        //尝试获取锁
//        boolean success = lock.tryLock(1200);
//        //判断获取锁是否成功
//        if (!success) {
//            //获取锁失败，返回错误信息
//            return Result.fail("不允许重复下单！");
//        }
//        //获取代理对象（事务）
//        try {
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            return proxy.createVoucherOrder(voucherId);
//        }
//         finally {
//            lock.unlock();
//        }
//
//    }

    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        //5.一人一单
        Long userId = voucherOrder.getUserId();
        //5.1查询订单
        Integer count = query().eq("user_id", userId).eq("voucher_id", voucherOrder.getVoucherId()).count();
        //5.2判断是否存在
        if (count > 0) {
            //用户已经购买过了
            log.error("用户已经购买过一次！");
            return;
        }
        //6.库存充足，扣减库存
        boolean success = voucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();
        if (!success) {
            //扣减失败
            log.error("用户已经购买过一次！");
            return;
        }

        //7.创建订单
        save(voucherOrder);
    }
}
